Low birefringent sensor substrate and methods thereof

Abstract

A resonant waveguide article, including: a polymeric substrate having at least one integral grating region, wherein the article has a low birefringence property of for example, from about 5 to 270 nm/cm, as defined herein. Also disclosed is a microplate including the resonant waveguide article, and an integral well plate bonded to the sensor article, as defined herein. Also disclosed are methods of making a sensor article, and a method of making and using the microplate including the sensor article, as defined herein.

1 . A resonant waveguide grating article, comprising:
 a polymeric substrate and the integral grating region;   wherein the article has a low birefringence property of from about 5 to 270 nm/cm.   
     
     
         2 . The article of  claim 1 , wherein the length and width dimensions of the substrate are about 4.7 by about 3 inches, the thickness of the substrate is from about 0.5 to about 1.5 millimeters having less than about 2% variation, and the grating height is about 0.05 to about 1 micrometer. 
     
     
         3 . The article of  claim 1 , wherein the substrate and the integral grating region comprise an optically transparent engineering resin. 
     
     
         4 . The article of  claim 3 , wherein the optically transparent engineering resin comprises a COC resin, a polystyrene resin, or a combination thereof. 
     
     
         5 . The article of  claim 1 , wherein the optical axis orientation of the birefringence is substantially parallel or perpendicular to the lines of at least one of the grating regions. 
     
     
         6 . The article of  claim 1 , wherein the article has power uniformity where the power of each of the sensors in the article is within about 30% of the maximum power of the sensor. 
     
     
         7 . The article of  claim 1 , further comprising an integral well plate directly bonded to the article to provide a microplate. 
     
     
         8 . The article of  claim 7 , wherein the microplate has optical alignment variation of less than 2 milliradians, flatness and parallelism variation such that the angle between the launch and reflected light beams is less than 2 milliradians for each of the sensors in the microplate. 
     
     
         9 . The article of  claim 7 , wherein the microplate has from 1 to 1536 wells. 
     
     
         10 . The article of  claim 1 , wherein the at least one integral grating region comprises a plurality of parallel grating lines. 
     
     
         11 . A method of making the article of  claim 1 , comprising:
 a single cavity injection molding to form the substrate having at least one grating feature on at least one surface of the substrate,   the mold being selected for the single cavity injection molding comprises a melt reservoir prior to a gate, the gate being about 30% of the width of the substrate mold cavity, the melt reservoir is situated in a runner leading to the gate, the melt reservoir enhances the parallelism of the injected resin flow, and the single cavity injection molding is accomplished at a high pack pressure of about 5,000 psi to about 10,000 psi, for from about 0.1 to 0.5 seconds, and then a long hold time of about 5 to about 10 seconds at a lower pressure at from about 2,000 psi to about 4,500 psi.   
     
     
         12 . The method of  claim 11 , wherein the optical axis orientation of the birefringence is substantially parallel to the lines of at least one grating region. 
     
     
         13 . The method of  claim 11 , wherein the single injection molding step to form a substrate having at least one grating region on at least one surface of the substrate is accomplished with a metal master containing the mirror image grating pattern on at least one half of the mold cavity. 
     
     
         14 . The method of  claim 11 , further comprising an assembly step to join the article and a well plate to form a unitary microplate assembly containing at least one well.